EP3008036B1 - Method and device for removing contaminants arising during the production of aliphatic nitrate esters - Google Patents

Description

The present invention relates to the technical field of preparation of nitric acid esters (also referred to as nitro esters or nitrate esters) mono- or polyhydric (cyclo) aliphatic alcohols (ie in other words the nitration of monohydric or polyhydric aliphatic or cycloaliphatic alcohols to the corresponding nitric acid esters ), in particular the purification of the obtained after removal of Nitrierendsäure nitrated Rohsalpetersäureester.

In particular, the present invention relates to a process for the removal of impurities arising in the preparation of aliphatic or cycloaliphatic nitric acid esters (such as in particular unreacted starting materials, reaction by-products, nitrating acid and their reaction products, such as nitrogen oxides or nitrous acid, etc.), in particular one Process for the removal of impurities from nitrided Rohsalpetersäureestern obtained in the nitration of nitratable monohydric or polyhydric aliphatic or cycloaliphatic alcohols after removal of the Nitrierendsäure.

Furthermore, the present invention relates to the use of a device for removing impurities resulting from the production of aliphatic or cycloaliphatic nitric acid esters, in particular the use of a device for removing impurities from the nitration of nitratable mono- or polyhydric aliphatic or cycloaliphatic alcohols after removal of the Nitrierendsäure resulting nitrated Rohsalpetersäureestern.

Finally, the present invention relates to the use of a production plant for the nitration of nitratable aliphatic or cycloaliphatic alcohols with subsequent purification of the nitrated crude products (ie, with subsequent purification of the resulting Rohsalpetersäureester) or the use of a production plant for the production of nitric acid esters of mono- or polyhydric aliphatic or cycloaliphatic alcohols subsequent purification of the nitrated crude products.

Aliphatic nitro esters (also referred to as aliphatic nitric acid esters, aliphatic nitrate esters or the like), such as. For example, pentaerythritol tetranitrate (PETN), glycerol trinitrate (NGL), ethylene glycol dinitrate (EGDN), ethylhexyl nitrate (EHN), etc., are generally used in a continuous operation (e.g., in the case of NGL, EGDN, or mixtures thereof, according to the methods of Schmid-Meissner or Biazzi, by the injector method or by the NAB process of Nielsen and Brunnberg or in the case of EHN by a modified method according to EP 1 792 891 A1 ) by reacting the corresponding alcohol (such as, for example, pentaerythritol, glycerol, ethylene glycol, ethylhexyl ethanol etc.) with nitric acid directly or alone or else in the presence of sulfuric acid as catalyst and water-binding agent. The nitration of the alcohols (ie their conversion to nitric acid esters) is generally carried out in the liquid phase, either as a pure substance or as a mixture or in solution in inert, water-immiscible solvents.

The resulting crude nitroesters (hereinafter synonymously also referred to as Rohsalpetersäureester, Rohnitratester, nitrated crude products or the like) must be subjected before their further processing of a multi-stage wash and additional purification steps to the still dissolved or suspended in the crude nitro esters impurities such. For example, sulfuric acid, nitric acid, nitrous, etc., and by-products from the oxidative degradation of the starting alcohols, and thus to improve the stability of nitroesters, which are highly sensitive explosives, to improve.

Usually, the scrubbing of the crude nitroester to remove the dissolved and suspended acids of the nitriding mixture and other acidic or otherwise extractable with the detergent impurities consists of three steps (see, for example, BT Urbanski, Vol 2, pages 97 ff., In particular Figs , 44, 59 and 60, Pergamon Press, Reprint 1985). The washing medium used is usually water. The laundry is generally carried out as a liquid / liquid wash with the nitroester liquid at wash temperature or as a solution thereof in a suitable solvent.

1. 1. eine saure Wäsche ("saure Wäsche") mit Wasser zur Entfernung der gelösten und suspendierten Mineralsäuren, wie z. B. Schwefelsäure, Salpetersäure und Nitrose;
2. 2. eine basische bzw. alkalische Wäsche ("basische Wäsche" oder "Alkaliwäsche") in Gegenwart einer Base, wie z. B. Natriumcarbonat (Soda), Natriumbicarbonat, Ammoniak, Natronlauge, Kalilauge etc., insbesondere zur Entfernung der im Nitratester nach der ersten Wäsche noch vorhandenen Mineralsäuren und Reste von Nitrose und anderen schwach acide Verunreinigungen aus einer oxidativen Zersetzung des eingesetzten Alkohols oder anderen aliphatischen oder cyclischen Kohlenwasserstoffen, die als Spuren im Ausgangsalkohol vorhanden waren;
3. 3. eine Wäsche mit Wasser ("Neutralwäsche") zur Entfernung der Restspuren von Alkali und der weiteren Reduzierung der noch in Spuren im Produkt verbliebenen Verunreinigungen.

This three-stage washing of the nitrated crude products (ie, the crude nitric or nitric acid esters) usually involves the following steps:

1. 1. an acidic wash ("acid wash") with water to remove the dissolved and suspended mineral acids, such. Sulfuric acid, nitric acid and nitrous acid;
2. 2. a basic or alkaline wash ("basic wash" or "alkali wash") in the presence of a base such. As sodium carbonate (soda), sodium bicarbonate, ammonia, caustic soda, potassium hydroxide, etc., in particular for removing the remaining in the nitrate ester after the first wash mineral acids and residues of nitrous and other weakly acidic impurities from an oxidative decomposition of the alcohol or other aliphatic or cyclic hydrocarbons present as traces in the starting alcohol;
3. 3. a wash with water ("neutral wash") to remove the residual traces of alkali and further reduce the remaining impurities in the product impurities.

But even a wash of the crude nitrate ester directly with soda solution, ie omitting the washing stage "acidic laundry", is partially practiced and is state of the art (see, for. BT Urbanski, Vol. 2, Biazzi-Process, pages 107 ff., In particular Fig. 48, Pergamon Press, Reprint 1985 ; T. Urbanski, Vol. 4, page 328, Pergamon Press 1984 ; Brunnberg, Industrial and Laboratory Nitration, ACS Symposium Series no. 22 (Editors: L.F. Albright and HJT Hanson), page 341, Washington DC, 1976 ).

The aim of these washing steps is, in addition to a pure product with high stability, to obtain as little wastewater as possible per tonne of product, whereby the leached impurities and the nitrate esters (traces) still present according to their solubility should be present in the wastewater in such a way that their disposal can be carried out inexpensively ,

To minimize the amount of water required for this wash and to recover the dissolved in the crude nitrate in considerable amounts acids, especially nitric acid, can -. In DE-PS 505 424 and DE-PS 546 718 described - the laundry with a reduced amount of wash water in the first washing step ("acid wash") are performed such that a Washing acid is obtained with a content of nitric acid of 20- to 60% strength or from 35 to 55% and up to 15% sulfuric acid. This wash acid can be worked up directly or together with the nitrating acid.

Furthermore, the washing can, for example, be carried out countercurrently in such a way that the washing water from the third washing step ("neutral washing") is used directly or after the addition of bases for washing the nitrate ester in the second washing step ("alkali washing") and this washing water from the second washing step (ie the alkaline washing step) in the first washing step (ie, the acidic wash) is introduced (see. DE-PS 505 424 and DE-AS 1 135 876 ).

It is customary for these three washing steps for safety reasons preferred injectors (jet pumps) to be used as conveyors with the washing medium as blowing agent between the individual washing steps, and the actual washing to take place in air-operated washing columns. After washing, the purified nitrate ester is transported as an emulsion with water in a warehouse or for further processing.

In the DE-PS 710 826 describes a process in which the three-stage washing of nitrate esters of polyhydric alcohols is carried out in countercurrent in air-stirred washing columns, wherein the nitrate esters are premixed with the scrubbing liquid in injectors and this premixed emulsion is fed via air injectors in the scrubbing column. At the end of the wash, the washed nitrate ester is transported to the storage after phase separation by means of injectors, which are operated with circulated motive water. Also in the T. Urbanski, Vol. 2, pp. 97 ff., In particular Figs. 59 and 60, Pergamon Press, reprint 1985, documented washing comes in the DE-PS 710 826 described washing method in conjunction with the injector used.

For a removal of a substance from a mixture by extraction / washing in a substance immiscible with this composition, as in this case the mixture of liquid nitrate ester impurities with water, it is necessary for a successful extraction of impurities from the mixture, the two immiscible So, as an oil-in-water emulsion (O / W emulsion), be it as a water-in-oil emulsion (W / O emulsion) - that it spreads over a sufficiently long time there is such a large exchange surface between the immiscible phases, that the distribution equilibrium for the substances to be extracted is achieved and the extracted substances in the extract phase can still be changed by subsequent reactions so that a back-extraction is no longer possible.

It is known that injectors or jet aspirators are suitable for mixing immiscible liquids, but that injectors are not suitable as a dispersing element for two liquids immiscible with one another. For a good wash, the drop sizes generated in the injector are not small enough. The stability of the emulsion produced is too low, and the exchange surface required for the optimum mass transfer is - in conjunction with the short residence time in the mixing tube of the injector (about 1 second) - thus too small.

The low-stable nitrate ester emulsions in water produced by injectors therefore tend to phase separate rapidly. This is particularly problematic for the transport of such emulsions over longer distances. Like in the DE-PS 973 718 descriptive described finds - if an emulsion is promoted by itself - easily in the long, little inclined delivery pipes separation into blasting oil and water instead. It can create a coherent explosive oil layer, which allows Durchdetonieren.

In order to prevent the coalescence of the nitrate ester after leaving the injector and to prevent a detonation by separated blasting oil especially during emulsion transport, are - as in the US 2,140,897 A , of the DE-PS 820 575 , of the DE-PS 973 718 , of the DE-AS 1 058 093 , of the DE-OS 1 571 221 or the DE-OS 2 055 093 - specified methods which allow to stabilize the emulsion of the nitrate ester in water or to prevent the formation of capable of detonation current threads from deposited nitrate esters. This is preferably done by admixing air or by re-emulsifying with air or by interrupting the emulsion stream with water or air.

However, it is known that gas bubbles in the liquid nitrate ester can not only substantially increase its impact sensitivity caused by adiabatic compression (cf. DE-OS 1 571 221 ), but that the two - phase mixtures of additionally mitangesaugter air, as already in the DE-AS 1 058 039 described, can lead to such stable emulsions that only by using centrifugal separators a phase separation is possible.

This risk of air entrapment in the liquid nitrate ester can by in the DE-OS 1 571 221 and the DE-OS 2 055 093 be prevented. By interrupting the homogeneous emulsion column in the transport line through a nitrate ester-free water column the formation of a detonating explosive filament is effectively prevented by too fast coalescence of the nitrate ester emulsified in the injector.

The less stable dispersions of nitrate ester in washing water produced by the injector with its relatively low dispersing power and vice versa and consequently the non-optimal exchange surface for effective washing (in addition to the very short dwell times in the injector mixing area) allow only incomplete removal of contaminants in the nitrate ester to be purified. Therefore, in order to achieve the desired levels of purification, the injectors are coupled with dwell-time containers with active dispersion.

As washing apparatuses are therefore usually used for washing the nitroester to be purified on the individual washing stages with air-operated wash columns ( DE-PS 710 826 ) in connection with injectors as means of transport or stirred tank cascades in Connection with injectors (T. Urbanski, Vol. 4, page 328, in particular Fig. 46, Pergamon Press 1984 ) used. The use of the air-stirred wash columns is complicated and expensive and no longer meets today's safety standards, according to which the presence of air bubbles in the nitrate ester should be avoided ( DE-OS 1 571 221 ). Even multi-stage stirred tank cascades are complicated and expensive.

Also, the use of injectors alone, ie without residence time, as in DE-AS 1 039 049 suggested, is complicated and expensive. In order to achieve optimal cleaning with injectors without residence time container and additional dispersing equipment, it is necessary to work in multiple stages in each washing step so that the purity and stability desired for the further processing of the nitrate ester can be obtained.

The emulsion transport of nitrate esters, as in DE-OS 1 571 221 and in the DE-OS 2 055 093 described, is not very suitable as an additional washing step because he has because of its generated by an injector unstable emulsion with relatively large drops only at most a polishing effect to remove traces of washing medium, which were still entrained as a microemulsion from the upstream washing stages.

document DE 10 39 049 B relates to a continuous process for the preparation of nitric acid esters and organic nitro compounds by nitration with nitrating acid, wherein the reaction components are supplied with a heat content suitable for the nitriding reaction in question and reacted in an injector with mixing, after which the reaction mixture is transferred to a separator, in which the nitro products produced are separated from the excess acid, the mixing taking place in an injector into which the nitrating acid is introduced under pressure, the other reactant being sucked from a reservoir into the injector under conditions such that the mixture of Reactants and the reaction is currently and essentially completely directly in the injector and thus takes place in a very limited space.

document WO 2012/156095 A1 relates to a process for the removal of impurities from the nitration of nitratable aromatic compounds after removal of Nitrierendsäure resulting nitrated crude products by treatment with a washing medium and a suitable apparatus for performing this method and apparatus and a corresponding production plant for nitration of nitrable aromatic compounds with subsequent purification nitrated products.

Overall, known from the prior art methods and plants for the purification of nitrate esters either not work with high efficiency, or they are no longer satisfactory from the standpoint of modern safety standards.

The present invention is therefore based on the object, a method and apparatus for removing impurities resulting from the production of aliphatic nitrate esters, in particular for removing impurities from nitrided Rohnitratestern obtained in the nitration of nitratable monohydric or polyhydric aliphatic alcohols after removal of the nitrating , As well as a (production) plant for the nitration of nitrable monohydric or polyhydric aliphatic alcohols with subsequent purification of the nitrated nitric esters provide, the above-described, occurring in connection with the prior art problems and disadvantages should be at least largely avoided.

In particular, it is an object of the present invention to provide a method and apparatus suitable for carrying out this method, with which an efficient purification of nitrate esters, such as those from the nitration of monohydric or polyhydric alcohols after removal of the so-called Nitrierendsäuren emerge, can be made possible.

A further object of the present invention is to wash the crude nitrate esters resulting from the removal of the nitrating agent or their solutions in inert solvents in which significant amounts of impurities, such as, for example, still entrained nitrating acid, dissolved sulfuric acid, nitric acid, nitrous oxide, degradation products from the oxidative Degradation of the starting alcohols, etc., so to speak, perform in one step in each washing step so that the washed nitrate esters are free of acids and water-soluble and acidic residues from the oxidative degradation of the starting alcohol to be nitrated and / or the product, thus the product thus treated meets the respective requirements for its stability, other safety-related requirements and other product specifications and thus increases the safety in the system by further reducing the amounts of nitrate ester in the system and thus closing Ch the effort and costs are much lower than in the previously used methods and devices of the prior art.

The above-described task is inventively achieved by a method according to claim 1; Further, advantageous developments and refinements of the method according to the invention are the subject of the relevant subclaims.

Another object of the present invention is the use of a device or a system according to the relevant independent claim (subclaim); Further advantageous developments and refinements of this aspect of the invention are the subject of the relevant subclaims.

In addition, the subject of the present invention is the use of a production plant according to the relevant independent claim (subclaim); Further advantageous developments and refinements of this aspect of the invention are the subject of the relevant subclaims.

It goes without saying that embodiments, embodiments, advantages or the like, which are subsequently - for the purpose of avoiding unnecessary repetition - carried out only to one aspect of the invention, of course, also apply accordingly with respect to the other aspects of the invention.

Furthermore, it goes without saying that in the case of subsequent statements of values, numbers and ranges, the values, numbers and ranges given in this context are not to be understood as limiting; It goes without saying for the person skilled in the art that it is possible to deviate from the stated ranges or details on a case-by-case basis or application-related basis without departing from the scope of the present invention.

In addition, it is true that all the values or parameter information or the like mentioned below can in principle be determined or determined using standardized or explicitly stated determination methods or determination methods which are familiar per se to the person skilled in the art.

Having said that, the present invention will be described in more detail below.

1. (a) zunächst werden die Rohsalpetersäureester (d. h. also die nach Abtrennung der Nitrierendsäure anfallenden nitrierten Rohprodukte) mit einem Waschmedium in Kontakt gebracht, wobei die Rohsalpetersäureester und das Waschmedium derart ineinander verteilt werden, dass eine Emulsion resultiert (d. h. mit anderen Worten wird in diesem ersten Verfahrensschritt (a) eine Emulsion bzw. Dispersion von nitrierten Rohprodukten einerseits und Waschmedium andererseits hergestellt); und
2. (b) nachfolgend wird die resultierende Emulsion in einen Rohrreaktor einspeist, wobei der Rohrreaktor mit Mischelementen, insbesondere zum Eintrag von zusätzlicher Mischenergie, ausgestattet ist, so dass während des Durchtritts der Emulsion durch den Rohrreaktor die in den Rohsalpetersäureestern anfänglich vorhandenen Verunreinigungen zumindest teilweise entfernt werden und/oder so dass während des Durchtritts der Emulsion durch den Rohrreaktor die in den Rohsalpetersäureestern anfänglich vorhandenen Verunreinigungen zumindest teilweise in das Waschmedium überführt und/oder hierdurch neutralisiert werden.

The subject of the present invention - according to a first aspect of the present invention - is thus a process for the removal of impurities resulting from the production of aliphatic or cycloaliphatic nitric esters (nitrate esters or nitro esters), in particular a process for the removal of impurities from the nitration of nitriles mono- or polyhydric aliphatic or cycloaliphatic alcohols after removal of the Nitrierendsäure resulting Rohsalpetersäureestern, by treatment with at least one washing medium, the method comprising the following steps:

1. (a) first, the crude nitric acid esters (ie, the nitrated crude products resulting from the removal of the nitrating acid) are contacted with a washing medium, the crude nitric acid esters and the washing medium being distributed into each other such that an emulsion results (ie, in other words Process step (a) produces an emulsion or dispersion of nitrated crude products on the one hand and washing medium on the other hand); and
2. (B) Subsequently, the resulting emulsion is fed into a tubular reactor, wherein the tubular reactor with mixing elements, in particular for the introduction of additional mixing energy, is equipped, so that during the passage of the emulsion through the tubular reactor, the impurities initially present in the Rohsalpetersäureestern are at least partially removed and / or so that during the passage of the emulsion through the tubular reactor, the impurities initially present in the crude nitric acid esters are at least partially transferred into the washing medium and / or neutralized thereby.

The process according to the invention is thus outstandingly suitable for purifying nitrated crude products obtained in the nitration of nitratable monohydric or polyhydric aliphatic alcohols (after separation of the nitrating acid) (ie in other words for purifying the resulting crude nitric acid esters).

The principle of the process according to the invention therefore consists, inter alia, of first contacting the nitrate-containing, still significant amounts of crude nitrate ester containing impurities, after removal of the nitrating end-acid (eg in a separator), with a washing medium and Mixture of nitrate ester to be purified and washing medium into an emulsion or dispersion into each other and then feed the resulting emulsion or dispersion in a tubular reactor so that the initially present in the nitrate ester to be purified impurities transferred into the washing medium or thereby neutralized and in this way a purified nitrate ester is formed.

Typical impurities to be removed include, for example, unreacted starting materials (ie in particular unreacted mono- or polyhydric aliphatic or cycloaliphatic starting alcohols and unreacted starting mineral acids, especially nitric acid and optionally sulfuric acid, if used as starting material) and reaction by-products (in particular reaction products of nitric acid, such as. Nitrous acid, nitrous acid, etc., and reaction by-products of the starting alcohols, such as oxidation products, such as carboxylic acids, aldehydes, ketones, degradation or cleavage products, carbon dioxide, etc.).

As the Applicant has found out in a completely surprising manner, the use of a tubular reactor with additional mixing elements - in combination with an upstream dispersing or emulsifying means - results in a particularly thorough mixing and particularly intimate and fine distribution of washing medium on the one hand and nitrate esters to be purified On the other hand, their solutions can be achieved, so that in this way the impurities can be completely or at least substantially completely removed, so to speak, in a single process step (namely within the scope of the tubular reactor treatment).

In contrast to the prior art, therefore, further complex process steps for the purification of the crude nitro ester are avoided in an efficient manner, without sacrificing quality in the purification of the crude nitrate esters. Also, the required safety standards are ensured by the inventive method.

Surprisingly, the tube reactor used according to the invention for the treatment of the crude nitrate ester with the washing medium with the additional mixing elements - in combination with the upstream dispersing device for producing the starting emulsion of washing medium and Rohnitroester - ensures such an intimate and fine distribution of crude nitroester on the one hand and washing medium on the other in the context of tube reactor treatment according to process step (b), all or at least substantially all impurities are transferred into the wash medium or neutralized thereby so that they are subsequently separated (ie after completion of process step (b) together with the wash medium from the then purified nitrate ester can be).

It has surprisingly been found that it is possible in the context of the present invention to carry out a wash of nitrate successfully quasi one-stage - even at high levels of contamination with impurities such as nitrating acid, nitric acid, etc. - by a simple and inexpensive Combination of jet pumps (injectors) or jet mixers (jet mixers or jet mixing devices ), but also other dispersing, in conjunction with additional facilities, such as static mixers, orifices, etc., in the downstream tubular reactor, what it does not allow to enter only a well-defined mixing energy in the mixture of immiscible phases, but also to ensure a residence time, which allows to proceed even slow subsequent reactions as quantitatively as possible. The thereby produced emulsions from the organ phase to be purified in the washing medium (O / W type) or the washing medium in the organ phase (W / O type) provide the required for an effective and optimal mass transfer interface between washing nitrate ester and washing medium.

A special feature of the present invention is also to be seen in the fact that the tubular reactor with mixing elements, in particular static mixing elements, for the entry of additional mixing energy is equipped (the mixing elements, for example, as plates, in particular baffle or baffles, as diaphragms, as a static mixer or can be designed as a flow divider). As a result, the originally present droplet size distribution is not only maintained, but adjusted in such a way that during the passage of the emulsion through the tubular reactor, the impurities initially present in the nitrated crude products are completely transferred into the washing medium and / or neutralized thereby.

As for the aliphatic nitric acid ester (nitrate ester) to be purified, it may be selected from any of nitric acid esters of monohydric or polyhydric aliphatic alcohols. In particular, the nitric acid ester to be purified can be selected from (i) nitric acid esters of aliphatic or cycloaliphatic monoalcohols, in particular of linear or branched aliphatic or cycloaliphatic monoalcohols, in particular of hexanols, heptanols, octanols, ethylhexyl alcohol and cyclohexanol; (ii) nitric acid esters of dihydric aliphatic alcohols, especially of ethylene glycol and propylene glycol and their oligomers and polymers such as ethylene or propylene diglycol, ethylene or propylene triglycol and polyethylene or polypropylene glycol; (iii) nitric acid esters of trihydric aliphatic alcohols, especially of trimethylolethane and glycerol; (iv) nitric acid esters of dihydric or polyhydric aliphatic alcohols, especially of pentaerythritol and dipentaerythritol.

As stated above, the tubular reactor used in process step (b) is equipped with mixing elements for introducing additional mixing energy. In this way, the originally existing droplet size distribution can not only be maintained, but rather adjusted such that during the passage of the emulsion through the tubular reactor, the impurities initially present in the nitrated crude products are transferred into the washing medium or neutralized thereby.

In particular, the mixing elements present in the tubular reactor are static elements, i. H. In particular, the mixing elements are designed as static mixing elements.

According to a particular embodiment, the mixing elements, in particular the static mixing elements, can be fixed on the inside in the tubular reactor, in particular be connected to the inner walls of the tubular reactor, preferably permanently or detachably connected.

According to a further particular, alternative embodiment, the mixing elements can be designed as insertion elements. In this case, the insertion elements can be inserted as needed as a function of the number and / or position in the tubular reactor or be positioned in the tubular reactor.

In particular, the mixing elements can be designed as sheets, in particular baffle or deflecting plates, as diaphragms, as static mixers or as flow dividers.

According to a further embodiment, 1 to 15 mixing elements, in particular 2 to 15 mixing elements, preferably 2 to 10 mixing elements, particularly preferably 2 to 5 mixing elements, are arranged in the tubular reactor. This leads to a particularly good emulsification of pipe products to be cleaned and washing medium.

In this context, it is also advantageous if a sufficient mixing energy for mixing of pipe products and washing medium is provided by the mixing elements in the tubular reactor. In this context, it is particularly advantageous if a mixing energy (i.e., volume-related mixing energy) of 20 to 1000 joules / liter, preferably 25 to 500 joules / liter, particularly preferably 30 to 200 joules / liter, is introduced overall in the tubular reactor.

In this context, pressure drop per mixing element should be 0.2 bar to 3.0 bar, preferably 0.3 to 1.5 bar, particularly preferably 0.3 to 0.8 bar.

Particularly suitable as mixing elements are static mixing elements, in particular in the form of so-called static mixers or static mixers. These are devices for mixing fluids, in which only the flow movement causes the mixing and which do not have moving elements. They consist of flow-bearing elements in a pipe; these alternately divide the material flow and then bring it back together, whereby the mixing is achieved.

According to the invention, it is thus provided in order to prevent coalescence of the washing emulsion after a short time and thus incomplete extraction of the impurities to be removed from the nitrate ester to be purified, that the tubular reactor for carrying out process step (b) with mixing elements, in particular for the entry of additional Mixing energy, is equipped; In this way, particularly good cleaning results can be achieved, as achieved by the additional mixing elements, a still further improved, particularly intimate distribution of washing medium on the one hand and aufzureinigendem nitrate ester on the other hand and can be maintained over the entire length of the tubular reactor. For the additional mixing elements, preferably over the Tubular reactor arranged distributed, it can be in particular sheets, especially baffles or baffles, diaphragms, static mixers, flow dividers or the like to maintain the emulsion of the type O / W or W / O. According to the invention, it is preferred if 1 to 15 mixing elements, in particular 2 to 15 mixing elements, preferably 2 to 10 mixing elements, more preferably 2 to 5 mixing elements, are present in the tubular reactor; these mixing elements can be distributed over the entire length of the tubular reactor. Preferably, the mixing elements can be inserted as a push-in element in the tubular reactor as needed.

As regards the preparation of the emulsion or dispersion in process step (a), this is generally carried out by means of a suitable dispersing or emulsifying device, in particular by means of a suitable mixing device.

In the context of the present invention can be used as dispersing or emulsifying, in particular as a mixing element, for example, a jet mixer (jet mixer) or a pump, in particular a jet pump (injector).

A jet pump (injector) is a pump in which the pumping action is generated by a fluid jet ("propellant") which, by momentum exchange, aspirates, accelerates and compresses / promotes another medium ("suction medium") when under sufficient pressure , As an injector, a jet pump is usually referred to, which generates an overpressure, which therefore has a predominantly compacting effect.

In the context of the present invention, the dispersing or emulsifying device, in particular the mixing element, can in particular produce a driving jet (central jet) and a ring jet surrounding the driving jet. In this case, the propulsion jet is preferably formed by the washing medium and the annular jet through the crude nitric esters to be purified.

According to a particular embodiment, it can be provided that a jet mixer (jet mixer) or a jet pump (injector) is used as the dispersing or emulsifying device, in particular as a mixing element. In this case, in particular the jet mixer or the jet pump can produce a preferably central propulsion jet and a medium surrounding the propulsion jet, in particular in the form of an annular jet, the propellant jet preferably passing through the scrubbing medium and the annular jet being to be purified Rohsalpetersäureester can be formed (in principle, the reverse mode is possible, ie aufzurinigende Rohsalpetersäureester as jet and washing medium as a ring stream, although this embodiment is less preferred).

In principle, all types of jet mixers or jet pumps can be used as jet mixers or jet pumps, which allow the nitrate ester or the washing medium to be washed to be washed by means of the central jet jet as free jet, which can basically consist of either the washing medium or the nitrate ester to be washed such that either the nitrate ester to be washed in the washing medium or the washing medium in the nitrate ester to be washed is distributed as an emulsion having a large boundary surface. Devices of this type are for example in Ullmann's Encyclopedia of Industrial Chemistry, 2003, 5th Ed., Vol. B4, pages 87/88 and 565 to 571 , or in Perry's Chemical Engineers' Handbook, McGraw-Hill Book Company, 1984, 6th Edition, pages 5-21 to 5-23 , or in the German Offenlegungsschrift DE 2 151 206 described.

As stated above, the (central) propulsion jet in the jet mixer can be the washing medium and the surrounding medium the crude nitrate ester to be purified; Alternatively, however, the (central) propulsion jet can be formed by the nitrated crude product to be purified and the medium surrounding the (central) propulsion jet by the washing medium. Both alternative embodiments lead to the desired result. According to the invention, however, it is preferred if the (central) propulsion jet in the jet mixer is the washing medium and the surrounding medium is the crude nitrate ester to be purified

Particularly good results with regard to the purification of the crude products to be purified are obtained when the dispersing or emulsifying device, in particular the mixing element, generates a propulsion jet (central jet) and a ring jet surrounding the propulsion jet (wherein preferably the propulsion jet passes through the washing medium and the annular jet passes through the ratio of the velocities between the propulsion jet on the one hand and the annular jet surrounding the propulsion jet on the other hand in the range from 1: 6 to 35: 1, preferably in the range of 1: 2 to 25: 1, particularly preferably in the range from 1: 1 to 12: 1. In this way, a particularly intimate and fine distribution of washing medium on the one hand and aufreininigendem crude product on the other hand and consequently achieves a particularly efficient purification.

The flow rate of the emulsion or dispersion of washing medium and crude products in the tubular reactor (i.e., after the dispersing device) should be adjusted in the range of 0.1 to 15.0 m / s, preferably 0.5 to 10 m / s.

According to one embodiment of the present invention, it may be provided that the dispersing or emulsifying device used in process step (a), in particular the mixing element upstream of the tubular reactor, is in particular immediately upstream. According to a particular embodiment of this embodiment, it can be provided that the dispersing or emulsifying device, in particular the mixing element, passes into the tubular reactor.

Equally, however, it is also possible for the dispersing or emulsifying device, in particular the mixing element, to be integrated into the tubular reactor or to be part of the tubular reactor. For this purpose, for example, the dispersing or emulsifying device can be arranged in the upper or upstream part of the tubular reactor. Such an embodiment is particularly possible if the dispersing device, in particular the mixing element, is designed as a jet mixer (jet mixer) or as a jet pump (injector).

As far as the residence time of the emulsion of washing medium on the one hand and crude nitrate ester on the other hand in the tubular reactor (washing apparatus) in process step (b) is concerned, this can vary within wide limits. It is particularly preferred if the residence time in the tubular reactor is 0.05 to 130 seconds, preferably 0.1 to 70 seconds, particularly preferably 1 to 35 seconds. In this way, particularly good washing results are achieved because, on the one hand, a sufficient minimum residence time, but on the other hand, an economic throughput is ensured.

In the context of the purification, the mass and phase ratio between the nitrated crude products to be purified on the one hand and the washing medium on the other hand are also important, which can each vary widely.

Particularly good results are obtained if the mass ratio between aufzurinierendes Rohsalpetersäureestern on the one hand and washing medium, especially freshly added wash medium, on the other hand in the range of 250: 1 to 1: 20, preferably in the range of 120: 1 to 1: 8, particularly preferably in the range of 12: 1 to 1: 3, is set.

Equally, particularly good results are obtained when the mass ratio between the crude nitric esters to be purified and the washing medium in the tubular reactor and / or washing apparatus is in the range from 30: 1 to 1: 6, preferably in the range from 15: 1 to 1: 5, particularly preferably in the range from 6: 1 to 1: 3, is set.

The adjustment of the mass or phase ratio is achieved by circulating the washing medium after phase separation. This ensures, on the one hand, an optimal exchange surface between the organ phase and the washing medium and, on the other hand, the shortest possible time for the phase separation in the phase separation apparatus.

The washing of the crude nitrate ester can usually be carried out as a liquid / liquid wash in pure form, but also in admixture with an additional inert solvent. These additional solvents may either be separated prior to further use or used directly as a solvent / nitrate ester mixture.

The washing medium used according to the invention is liquid under process conditions, in particular at temperatures above 5 ° C., preferably at temperatures above 25 ° C., and at atmospheric pressure. According to the invention, it is preferred if the washing medium is based on water, preferably water.

Depending on the mass or phase ratio in the tubular reactor (washing apparatus) of the nitrate ester to be washed in the washing medium as an oil-in-water emulsion (O / W emulsion) or the washing medium in the nitrate ester to be washed as a water-in-oil emulsion (W / O emulsion).

According to a preferred embodiment, the process according to the invention can be carried out continuously (although in principle a discontinuous procedure is also possible). For large-scale implementation, a continuous implementation is preferred in any case.

In principle, the process according to the invention can be used to carry out an acidic wash and / or a basic wash and / or a neutral wash of the crude nitric esters to be purified.

In other words, the method according to the invention is basically suitable for carrying out the acidic wash and / or the basic wash and / or the neutral wash of the nitrated crude products or the crude nitric acid esters. The inventive method can thus be used in all three aforementioned washing steps. Equally, however, it is also possible for the process according to the invention to be used only for one or two washing stages, for example only for the acidic laundry or else only for the basic laundry or else only for the neutral laundry. So z. B. the nitrate ester typical emulsion transport of nitrate esters between the individual process steps of a production plant and / or for further processing after the laundry are formed according to the inventive method. In this regard, the method according to the invention can be used flexibly.

According to a particular embodiment of the present invention, the method according to the invention, in particular the method steps (a) and (b), can be carried out repeatedly or be carried out several times. The (partially) purified Rohsalpetersäureester resulting after each process run are re-fed to the subsequent process run.

In this particular embodiment, it can be provided that at least one process run is carried out as a basic wash and / or with a basic wash medium and at least one downstream process run is performed as a neutral wash and / or with a neutral wash medium.

Alternatively, it can also be provided that two, preferably three successive process runs are performed, which optionally a first wash with an acidic wash medium ("acid wash"), this followed by a second wash with a basic wash medium ("basic wash") and in turn, downstream of this, a third wash with a neutral wash medium ("neutral wash") include.

The efficiency of the washing medium can be further increased by adding at least one base to the washing medium, as described below.

In other words, it can be provided according to the invention that at least one base is added to the washing medium, in particular for carrying out a basic wash. This base may in particular be selected from the group of inorganic hydroxides, carbonates, bicarbonates and ammonia and mixtures or combinations thereof.

The amount of alkali used in an alkaline wash should be so high that not only can all the acids be quantitatively converted to their salts, but an excess of base should be used so that the pH in the wash liquor is so high that Even weak acids can be washed out quantitatively. In particular, it is advantageous in this context if the content of base in the washing medium is 0.01 to 0.4 mol / l, preferably 0.02 to 0.2 mol / l. In particular, the content of base in the washing medium should be at least twice the amount of alkali required for neutralization of all substances containing salts forming salts as impurities.

As already stated above, the crude nitric acid esters to be purified are liquid under process conditions. Optionally, the purified to be purified Rohsalpetersäureester in an inert solvent, such. As in halogenated hydrocarbons, especially methylene chloride, dichloroethane, etc., or in other solvents that do not interfere with the further processing or used in further processing.

The process step (b) may then be followed by separation of the nitric acid esters freed from the impurities from the washing medium, preferably in a phase separator (separator).

As a phase separator or phase separation apparatus all types of static separators can be used, but also dynamic separators, such as centrifugal separators. The separation time of the emulsion nitrate ester / washing medium depends, in addition to the density difference between the two phases, of the emulsion type (W / O or O / W) and the enlisted mixing energy, also on the excess of base in the washing medium, which is not required for neutralization , At entry of equal mixing energy, the separation time decreases significantly with increasing Base concentration in the washing medium. In order to accelerate the phase separation but also surface-active agents or mechanical separation aids, such as packages, dividing plates, etc., can be used. Also by a matched to the nitrate ester and emulsion type distance between the individual mixing elements, the phase separation can be accelerated.

According to an advantageous embodiment of the method according to the invention, it is provided that the washing medium, in particular after separation of the freed from the impurities nitrated nitric acid ester from the washing medium, is recycled. In this way, efficient washing is made possible and the amount of washing medium is reduced to a minimum.

To remove impurities with high partition coefficients in favor of the nitrate ester to be washed, high mass transfer resistances in the organ phase and slow further reactions of the extracted impurities in the washing medium, such as. As nitrous or nitrogen dioxide, the residence time in the subsequent reactor should be adapted to these conditions. According to a particular embodiment of the method according to the invention, this z. B. by a combination of the facilities described above to produce an optimal wash emulsion together z. B. be achieved with stirred tanks to ensure the necessary residence time for the phase transfer and subsequent reaction.

The dispersion / emulsion present at the end of the mixing section can be separated again into the individual phases in a phase separation apparatus (separator or settler). The washing medium with the impurities contained therein can either be supplied as waste water to a wastewater treatment or introduced in countercurrent to the upstream washing stage.

The washed nitrate ester can either be fed into the subsequent washing stage or transferred at the end of the wash directly for further processing or in an intermediate storage.

Optionally, after washing or after separation of the washing medium (for example after separation of the washing emulsion in a static separator or by a centrifugal separator) traces of suspended and dissolved water can be removed from the purified nitrate ester by additional drying from the purified nitrate ester , if desired.

• Insbesondere ermöglicht das erfindungsgemäße Verfahren eine effiziente Aufreinigung von aus bei der Nitrierung von nitrierbaren ein- und mehrwertiger (cyclo)aliphatischen Alkoholen nach Abtrennung der Nitrierendsäure anfallenden nitrierten Rohprodukten mit nur geringer Komplexität und großer Verfahrensökonomie wie Verfahrenseffizienz.

As described above, the method according to the invention is associated with a multiplicity of advantages and special features, of which a few advantages and special features are to be listed below, but not in a conclusive and non-restrictive manner:

• In particular, the process according to the invention makes it possible to efficiently purify nitrated crude products obtained in the nitration of nitratable monohydric and polyhydric (cyclo) aliphatic alcohols after removal of the nitrating end-product with only low complexity and high process economy such as process efficiency.

The tubular reactor used according to the invention for the purification of the crude nitration products allows the generation of large exchange surfaces for a two-phase mixture of washing medium on the one hand and crude nitrate ester on the other hand, so that in this way an effective mass transfer and rapid transfer of the impurities into the washing medium or in the case acidic compounds a rapid neutralization is ensured.

The process of the invention allows a rapid and almost efficient removal of the originating from the nitration impurities from the nitrated crude products, the washing medium after the treatment of the nitrate ester can be readily recycled or circulated.

Furthermore, the consistent use of the method according to the invention further improves the general safety when handling the highly sensitive multiply nitrated nitrate esters, such as NGL or EGDN. The quantities of explosives present in the plant will be further reduced.

The tube reactor used according to the invention with additional mixing elements not only allows an efficient and intimate distribution of washing medium on the one hand and nitrated (cyclo) aliphatic alcohol on the other hand, but by the targeted adjustment of a defined dispersion of the nitrate ester to be washed in the washing medium over the entire length of the tubular reactor, taking into account the permissible tube cross-sections, a partial coalescence of the dispersed nitrate ester in the tubular reactor reliably prevented and thus the formation of current strands of deposited nitrate ester, which could transmit a detonation.

The process according to the invention is suitable for carrying out the acidic wash and / or the basic wash and / or the neutral wash of the nitrated crude products. The inventive method can thus be used in all three aforementioned washing steps. Equally, however, it is also possible to use the process according to the invention for only one or two washing stages, for example only for the acidic laundry or else only for the basic laundry or else only for the neutral laundry. Thus, e.g. the emulsion transport of nitrate esters, which is typical for nitrate esters, is formed between the individual process stages of a production plant and / or for further processing after the laundry in accordance with the process according to the invention. In this regard, the method according to the invention can be used flexibly.

1. (a) mindestens eine Dispergiereinrichtung, insbesondere mindestens ein Mischorgan, zum Inkontaktbringen und Emulgieren von aufzureinigenden Rohsalpetersäureestern einerseits und Waschmedium andererseits; und,
2. (b) stromabwärts zur Dispergiereinrichtung angeordnet, einen Rohrreaktor zur Einspeisung der in der Dispergiereinrichtung erzeugten Emulsion von aufzureinigenden Rohsalpetersäureestern einerseits und Waschmedium andererseits, wobei der Rohrreaktor mit Mischelementen, insbesondere zum Eintrag von zusätzlicher Mischenergie, ausgestattet ist, so dass während des Durchtritts der Emulsion durch den Rohrreaktor die in den Rohsalpetersäureestern anfänglich vorhandenen Verunreinigungen zumindest teilweise entfernt werden und/oder so dass während des Durchtritts der Emulsion durch den Rohrreaktor die in den Rohsalpetersäureestern anfänglich vorhandenen Verunreinigungen zumindest teilweise in das Waschmedium überführt und/oder hierdurch neutralisiert werden;
3. (c) stromabwärts zum Rohrreaktor angeordnet, eine Abtrenneinrichtung, insbesondere eine Scheideeinrichtung (Scheider), zur Abtrennung der von den Verunreinigungen befreiten nitrierten Produkte vom Waschmedium angeordnet ist.

Another object of the present invention - according to a second aspect of the present invention - is the use of a device (plant) for removing in the production of aliphatic or cycloaliphatic nitric acid esters (nitrate esters) resulting impurities, in particular for the removal of impurities from the nitration of nitridable mono- or polyhydric aliphatic or cycloaliphatic alcohols after removal of the Nitrierendsäure resulting Rohsalpetersäureestern, by treatment with at least one washing medium, wherein the inventively used device is particularly suitable for carrying out a method as described above,
the device comprising the following devices:

1. (A) at least one dispersing device, in particular at least one mixing element, for contacting and emulsifying to be purified Rohsalpetersäureestern on the one hand and washing medium on the other hand; and,
2. (B) arranged downstream of the dispersing device, a tubular reactor for feeding the emulsion produced in the dispersing of aufreiinigenden Rohsalpetersäureestern on the one hand and washing medium on the other hand, wherein the tubular reactor with mixing elements, in particular for the introduction of additional mixing energy, is equipped, so that during the passage of the emulsion through the tubular reactor, the impurities initially present in the Rohsalpetersäureestern are at least partially removed and / or so that during the passage of the emulsion through the tubular reactor, the impurities present in the Rohsalpetersäureestern initially at least partially transferred to the wash medium and / or neutralized thereby;
3. (C) arranged downstream of the tubular reactor, a separation device, in particular a separating device (separator), arranged to separate the nitrified products freed of the impurities from the washing medium.

As described above in connection with the method according to the invention, the dispersing device, in particular the mixing element, as a jet mixer (jet mixer) or pump, in particular jet pump (injector) may be formed.

As described in the same way above in the context of the method according to the invention, the dispersing device, in particular the mixing device, may be designed such that it generates a propulsion jet (central jet) and a ring jet surrounding the propulsion jet.

As described in the same way in connection with the method according to the invention, the dispersing device, in particular the mixing element, can be designed as a jet mixer (jet mixer) or jet pump (injector). In this case, the jet mixer or the jet pump can in particular be designed such that a preferably central driving steel and a medium surrounding the driving jet, in particular in the form of a ring beam, can be generated.

As already described above in connection with the method according to the invention, the dispersing device, in particular the mixing element upstream of the reactor, in particular immediately upstream, be, according to a particular embodiment, the dispersing device, in particular the mixing device, can pass into the tubular reactor.

According to an alternative embodiment, the dispersing device, in particular the mixing device, be integrated into the tubular reactor and / or be part of the tubular reactor. In this regard, reference may be made to the above statements in connection with the method according to the invention.

As explained above in the description of the method according to the invention, the tubular reactor is equipped with mixing elements, in particular for introducing additional mixing energy. For further details, reference may be made to the inventive method.

In the context of the apparatus used according to the invention, a single, two or three stage wash of the crude nitriding product can be carried out (that is to say acidic laundry and / or basic laundry and / or neutral laundry).

Furthermore, it is provided according to the invention that - arranged downstream of the tube reactor - a separation device, in particular a separating device (separator), is arranged to separate the freed of the impurities nitrided products from the washing medium.

Furthermore, in the context of the device used according to the invention, there is the possibility that a stirred tank and / or a stirred reactor is arranged downstream of the tube reactor and upstream of the separating device (in other words, between tube reactor and separating device). In particular, in this way the contact and / or residence time between nitrated products (nitric esters) on the one hand and the washing medium on the other hand is extended.

For further details of the device or system used according to the invention can be made to avoid unnecessary repetition of the above statements on the method according to the invention, which apply accordingly with respect to the device or system used according to the invention.

1. (a) eine Nitriereinheit zur Herstellung von Salpetersäureestern ein- oder mehrwertiger aliphatischer oder cycloaliphatischer Alkohole und/oder zur Nitrierung ein- oder mehrwertiger aliphatischer oder cycloaliphatischer Alkohole, insbesondere mit einem oder mehreren entsprechenden Reaktionsbehältern zur Durchführung der Nitrierreaktion(en);
2. (b) gegebenenfalls, in Produktionslinie stromabwärts zur Nitriereinheit angeordnet, eine Abtrenneinrichtung, insbesondere eine Scheideeinrichtung (Scheider), insbesondere zur Abtrennung der Nitrierendsäure von den nitrierten Rohprodukten (Rohsalpetersäureestern);
3. (c) in Produktionslinie stromabwärts zur Nitriereinheit und zur gegebenenfalls vorhandenen Abtrenneinrichtung angeordnet, eine Wascheinrichtung zur Durchführung einer Wäsche der nitrierten Rohprodukte, wobei die Wascheinrichtung umfasst:
   • mindestens eine Dispergiereinrichtung, insbesondere mindestens ein Mischorgan, zum Inkontaktbringen und Emulgieren von aufzureinigenden Rohsalpetersäureestern einerseits und Waschmedium andererseits; und,
   • stromabwärts zur Dispergiereinrichtung angeordnet, einen Rohrreaktor zur Einspeisung der in der Dispergiereinrichtung erzeugten Emulsion von aufzureinigenden Rohsalpetersäureestern einerseits und Waschmedium andererseits, wobei der Rohrreaktor mit Mischelementen, insbesondere zum Eintrag von zusätzlicher Mischenergie, ausgestattet ist, so dass während des Durchtritts der Emulsion durch den Rohrreaktor die in den Rohsalpetersäureestern anfänglich vorhandenen Verunreinigungen zumindest teilweise entfernt werden und/oder so dass während des Durchtritts der Emulsion durch den Rohrreaktor die in den Rohsalpetersäureestern anfänglich vorhandenen Verunreinigungen zumindest teilweise in das Waschmedium überführt und/oder hierdurch neutralisiert werden;
4. (d) gegebenenfalls, in Produktionslinie stromabwärts zur Wascheinrichtung angeordnet, einen Rührkessel, insbesondere zur Erhöhung der Kontakt- und/oder Verweilzeit zwischen Salpetersäureestern einerseits und Waschmedium andererseits;
5. (e) in Produktionslinie stromabwärts zur Wascheinheit und zum gegebenenfalls vorhandenen Rührkessel angeordnet, eine Abtrenneinrichtung, insbesondere eine Scheideeinrichtung (Scheider), insbesondere zur Abtrennung der von den Verunreinigungen befreiten Salpetersäureester vom Waschmedium.

Finally, another object of the present invention - according to a third aspect of the present invention - the use of a production plant for the production of nitric acid esters of mono- or polyhydric aliphatic or cycloaliphatic alcohols and / or for the nitration of mono- or polyhydric aliphatic or cycloaliphatic alcohols with subsequent purification of at the nitration resulting nitrated crude products,
the production plant comprises the following units:

1. (A) a nitrating unit for the preparation of nitric acid esters of mono- or polyhydric aliphatic or cycloaliphatic alcohols and / or for the nitration of mono- or polyhydric aliphatic or cycloaliphatic alcohols, in particular with one or more corresponding reaction vessels for carrying out the nitration reaction (s);
2. (b) optionally, arranged downstream of the nitriding unit in the production line, a separating device, in particular a separating device (separator), in particular for separating the nitrating end acid from the nitrated crude products (crude nitric acid esters);
3. (c) arranged in the production line downstream of the nitriding unit and the optionally present separating device, a washing device for carrying out a washing of the nitrated crude products, wherein the washing device comprises:
   • at least one dispersing device, in particular at least one mixing element, for contacting and emulsifying crude nitric esters to be purified on the one hand and washing medium on the other hand; and,
   • arranged downstream of the dispersing device, a tubular reactor for feeding the emulsion produced in the disperser of aufzurinierendes Rohsalpetersäureestern on the one hand and washing medium on the other hand, wherein the tubular reactor with mixing elements, in particular for the entry of additional mixing energy is equipped, so that during the passage of the emulsion through the tubular reactor the contaminants initially present in the crude nitric acid esters are at least partially removed and / or so that during the passage of the emulsion through the tubular reactor, the impurities initially present in the crude nitric acid esters are at least partially transferred to the wash medium and / or neutralized thereby;
4. (d) optionally, arranged downstream of the washing device in the production line, a stirred tank, in particular for increasing the contact and / or residence time between nitric esters on the one hand and washing medium on the other hand;
5. (E) arranged downstream of the washing unit and optionally existing stirred tank in production line, a separating device, in particular a separating device (Scheider), in particular for separating the freed from the impurities nitric acid ester from the washing medium.

In other words, in the production plant used according to the invention, the above-described apparatus or plant for purification, d. H. for the removal of impurities, part of this production plant, namely in the form of the washing unit or washing device (c).

As already described above, the mixing elements in the tube reactor can be static mixing elements or can be formed as static mixing elements.

According to a particular embodiment, the mixing elements, in particular the static mixing elements, can be fixed on the inside in the tubular reactor, in particular permanently or detachably connected to the inner walls of the tubular reactor.

Alternatively, however, the mixing elements can also be designed as insertion elements. In this case, the insertion elements can be inserted according to the number and / or position in the tubular reactor or positioned in the tubular reactor, if necessary.

As described above, the mixing elements can be designed as plates, in particular baffle plates or baffles, as diaphragms, as static mixers or as flow dividers.

In particular, 1 to 15 mixing elements, in particular 2 to 15 mixing elements, preferably 2 to 10 mixing elements, more preferably 2 to 5 mixing elements, may be arranged in the tubular reactor.

As stated above, it is advantageous if a mixing energy (ie volume-related mixing energy) of from 20 to 1000 joules / liter, preferably 25 to 500 joules / liter, particularly preferably 30 to 200 joules / liter, is introduced by the mixing elements in the tubular reactor and / or if the pressure drop per mixing element is 0.2 bar to 3.0 bar, preferably 0.3 to 1.5 bar, particularly preferably 0.3 to 0.8 bar.

As already described above in connection with the method according to the invention and the device or system used according to the invention, the dispersing device, in particular the mixing element, can be designed as a jet mixer or pump, in particular a jet pump (injector).

Furthermore, the dispersing device, in particular the mixing element, may be designed such that it generates a propulsion jet (central jet) and a ring jet surrounding the propulsion jet.

According to a particular embodiment, the dispersing device, in particular the mixing element, can be designed as a jet mixer (jet mixer) or jet pump (injector). In this case, the jet mixer or the jet pump may be designed such that a preferably central driving steel and a medium surrounding the propulsion jet, in particular in the form of a ring beam, can be generated.

As already described above, the dispersing device, in particular the mixing device, upstream of the reactor, in particular immediately upstream, be. In this embodiment, the dispersing device, in particular the mixing element, can pass into the tubular reactor.

According to an alternative embodiment, the dispersing device, in particular the mixing element, but also be integrated into the tubular reactor or be part of the tubular reactor.

For further details on the production plant used according to the invention, reference may be made to the above statements regarding the method according to the invention and to the apparatus or installation used according to the invention, which apply correspondingly in relation to the production plant used in accordance with the invention.

The method according to the invention and the apparatus or system for purification used in accordance with the invention and the production apparatus for nitriding used in accordance with the invention are illustrated by way of example and in a nonlimiting manner in the attached figure representations.

Fig. 1

eine schematische Darstellung einer einstufigen Wäsche für rohe Nitratester nach dem erfindungsgemäßen Verfahren bzw. mit der erfindungsgemäß eingesetzten Vorrichtung;

Fig. 2

eine detailliertere Darstellung einzelner Teile der Vorrichtung nach der schematischen Darstellung des erfindungsgemäßen Verfahrens gemäß Fig. 1;

Fig. 3

eine schematische Darstellung eines Ablaufs des erfindungsgemäßen Verfahrens bzw. eine schematische Darstellung der erfindungsgemäß eingesetzten Vorrichtung bzw. Anlage gemäß einem bevorzugten Ausführungsbeispiel der Erfindung für die üblichen drei Waschstufen einer Wäsche von Nitratestern;

Fig. 4

eine schematische Darstellung einer erfindungsgemäß eingesetzten Produktionsanlage zur Nitrierung nitrierbarer ein- und mehrwertiger Alkohole mit nachfolgender Wäsche der erhaltenen Nitratester gemäß einem bevorzugten Ausführungsbeispiel der Erfindung.

Further advantages, features, aspects and features of the present invention will become apparent from the following description of illustrated in the drawings, according to the invention preferred embodiments. It shows:

Fig. 1

a schematic representation of a single-stage wash for crude nitrate esters by the method according to the invention or with the device used in the invention;

Fig. 2

a more detailed representation of individual parts of the device according to the schematic representation of the method according to the invention Fig. 1 ;

Fig. 3

a schematic representation of a sequence of the method according to the invention or a schematic representation of the device or system according to the invention used according to a preferred embodiment of the invention for the usual three washing stages of a wash of nitrate esters;

Fig. 4

a schematic representation of a production plant according to the invention used for the nitration of nitrable monohydric and polyhydric alcohols with subsequent washing of the resulting nitrate esters according to a preferred embodiment of the invention.

Fig. 1 shows - in a schematic representation - an embodiment of a washing stage by the method according to the invention or with the apparatus or system according to the invention for the washing of crude nitrate esters with the washing medium as a propulsion jet.

The raw nitrate ester NE1 (n-1) to be washed with n = 1-3 becomes, after the removal of the nitrating end acid in a wash WW1 (n-1) with n = 1-3 - ie in an acidic wash WS with n = 1 or after the removal of all other weakly acidic substances still dissolved in the nitrate ester from the oxidative degradation of impurities in the presence of bases in an alkaline wash WA with n = 2 or in a neutral wash WN with n = 3 - in a mixing device SMn, 1 with n = 1-3, preferably in a jet pump (injector) or a jet mixer, with the washing medium WW10 (fresh water) or WW1n with n = 1-3, which serves as a propulsion jet in the case shown, brought together and directly into a tubular reactor C, which additional mixing elements Mn, m + 1 with n = 1-3 and with m = 1-15 contains introduced.

The washing emulsion from the tubular reactor is separated directly or, if necessary, after an extended residence time in a residence time vessel (eg in a stirred tank R, etc.) in a separating device Sn with n = 1-3 into the phases.

The washed nitrate ester NE1n with n = 1-3 is released either into the subsequent washing stage or as finished product NE13 for further processing. The loaded washing medium WW1n with n = 1-3 is either discharged directly as wastewater or recycled as a partial flow to set a defined phase ratio between nitrate ester and washing medium. This recycled partial stream can either be fed directly into the tubular reactor together with the newly added wash water as propellant jet or as a circulating stream.

The figure representations according to Fig. 2a-2c show those in the Fig. 1 schematically shown mixing devices SMn, 1 with n = 1-3 as a jet pump ( Fig. 2a ) and as a jet mixer ( Fig. 2b ), where V1 stands for the propulsion jet (preferably washing medium) and V2 for the nitrate ester. In Fig. 2c In addition, a possible arrangement of the static mixing elements Mn, 2, Mn, 3 Mn, 4, Mn, m-1, Mn, m and Mn, m + 1 in the tubular reactor, and distributed over the entire length of the tubular reactor shown.

1. a) In Schritt 1 werden in einer einstufigen sauren Wäsche WS die im rohen Nitratester NE 10 suspendierte und gelöste Schwefel- und Salpetersäure durch Wäsche mit Frischwasser WW 10 entfernt. Das Waschwasser WW 10 und zurückgeführtes Waschwasser WW 11 als Treibstrahl werden mittels Pumpe P zusammen mit dem zu waschenden Nitratester NE 10 mit einer Strahlpumpe (Injektor) oder über einen Strahlmischer direkt in einen Rohrreaktor eingespeist, der zusätzliche Mischelemente M1,m+1 enthält. Nach Durchlauf durch den Rohrreaktor wird die gebildete Emulsion in einem Scheider S1 getrennt. Das Waschmedium wird nach Phasentrennung entweder als Abwasser WW 11 direkt abgegeben, oder aber alternativ hierzu wird eine Teilmenge zusätzlich im Kreis geführt, um ein vorgegebenes Phasenverhältnis und damit einen definierten Emulsionstyp einzustellen. Der von Mineralsäuren befreite Nitratester NA 11 wird in Waschstufe 2, die alkalische Wäsche WA, eingespeist.
2. b) In Schritt 2 werden in einer einstufigen alkalischen Wäsche WA alle noch gelösten Mineralsäuren und andere acide Stoffe aus dem oxidativen Abbau von Verunreinigungen, entfernt. Das Waschwasser WW 13 aus der Neutralwäsche und zurückgeführtes Waschwasser WW12 als Treibstrahl werden unter Zusatz einer Base mittels Pumpe P zusammen mit dem zu waschenden Nitratester NE 11 aus der sauren Wäsche WS mit einer Strahlpumpe (Injektor) oder über einen Strahlmischer direkt in einen Rohrreaktor eingespeist, welcher zusätzliche Mischelemente M2,m+1 enthält. Nach Durchlauf durch den Rohrreaktor wird die gebildete Emulsion in einem Scheider S2 getrennt. Das Abwasser WW 12 mit einem pH größer als 7,5 wird entweder direkt abgegeben, oder aber alternativ kann eine Teilmenge im Kreis geführt werden, um ein vorgegebenes Phasenverhältnis und damit einen definierten Emulsionstyp einzustellen. Der von allen Mineralsäuren und anderen aciden Stoffen aus dem oxidativen Abbau von Verunreinigungen befreite Nitratester NA 12 wird in die Waschstufe 3, die Neutralwäsche WN, eingespeist.
3. c) In Schritt 3 werden in einer einstufigen Neutralwäsche WN die mitgerissenen Spuren an Waschmedium aus der alkalischen Wäsche entfernt. Das Waschwasser WW 10 und zurückgeführtes Waschwasser WW 13 als Treibstrahl werden mittels Pumpe P zusammen mit dem zu waschenden Nitratester NE 12 mit einer Strahlpumpe (Injektor) oder über einen Strahlmischer direkt in einen Rohrreaktor eingespeist, welcher zusätzliche Mischelemente M3,m+1 enthält. Nach Durchlauf durch den Rohrreaktor wird die gebildete Emulsion in einem Scheider S3 getrennt. Das Waschmedium, das die Restspuren an Alkali und Verunreinigungen enthält, wird entweder als Abwasser WW 13 direkt in die zweite Waschstufe WA eingeführt, oder aber alternativ kann eine Teilmenge zusätzlich im Kreis geführt werden, um ein vorgegebenes Phasenverhältnis und damit einen definierten Emulsionstyp einzustellen. Der von Mineralsäuren und anderen aciden Stoffen aus dem oxidativen Abbau von Verunreinigungen und Restspuren Alkali befreite Nitratester NE 13 wird direkt zur Weiterverarbeitung oder nach Abtrennung von möglicherweise vorhandenen inerten Lösungsmitteln in ein Zwischenlager abgegeben.

Fig. 3 shows an example of the process according to the invention in three steps for the separate removal of mineral acids by acid scrubbing (WS), for the removal of all otherwise present weakly acidic substances from the oxidative degradation of impurities in the presence of alkaline bases by means of alkaline scrubbing (WA ) and for the removal of traces of entrained alkaline wash by means of neutral washing (WN):

1. a) In step 1, in a single-stage acidic wash WS, the sulfur nitrate and nitric acid suspended in the crude nitrate ester NE 10 and removed by washing with fresh water WW 10. The washing water WW 10 and returned washing water WW 11 as propulsion jet are fed by pump P together with the to be washed nitrate NE 10 with a jet pump (injector) or via a jet mixer directly into a tubular reactor containing additional mixing elements M1, m + 1. After passing through the tubular reactor, the emulsion formed is separated in a separator S1. The washing medium is discharged directly after phase separation either as WW 11 wastewater, or alternatively a subset is additionally circulated to set a predetermined phase ratio and thus a defined emulsion type. The mineral acid-freed nitrate ester NA 11 is fed into wash stage 2, the alkaline wash WA.
2. b) In step 2, in a single-stage alkaline wash WA, all remaining mineral acids and other acidic substances are removed from the oxidative degradation of impurities. The wash water WW 13 from the neutral wash and returned washing water WW12 as propellant jet are fed with the addition of a base by means of pump P together with the nitratester NE 11 to be washed from the acid wash WS with a jet pump (injector) or via a jet mixer directly into a tubular reactor, which contains additional mixing elements M2, m + 1. After passing through the tubular reactor, the emulsion formed is separated in a separator S2. The WW 12 wastewater having a pH greater than 7.5 is either discharged directly or, alternatively, a subset may be circulated to adjust a given phase ratio and thus a defined type of emulsion. The nitrate ester NA 12 freed of all mineral acids and other acidic substances from the oxidative degradation of impurities is fed into the washing stage 3, the neutral washing WN.
3. c) In step 3, the entrained traces of washing medium are removed from the alkaline wash in a single-stage neutral wash WN. The washing water WW 10 and returned washing water WW 13 as propulsion jet are fed by pump P together with the to be washed nitrate NE 12 with a jet pump (injector) or via a jet mixer directly into a tubular reactor containing additional mixing elements M3, m + 1. After passing through the tubular reactor, the emulsion formed is separated in a separator S3. The washing medium, which contains the residual traces of alkali and impurities, is introduced either as waste water WW 13 directly into the second washing stage WA, or alternatively, a subset can be additionally circulated to set a predetermined phase ratio and thus a defined emulsion type. The nitrate ester NE 13, freed of mineral acids and other acidic substances from the oxidative decomposition of impurities and traces of alkali, is released directly into an interim storage facility for further processing or, after removal of potentially inert solvents.

Fig. 4 shows an example of a production plant used according to the invention for the production of nitrate esters with integrated laundry according to the invention of the crude nitrate esters from an isothermal or adiabatic nitration. The crude nitrate ester NE 10 formed in the nitriding unit N by reaction of the alcohol to be nitrated with nitric acid in the presence of sulfuric acid is washed after removal of the nitrating acid in the separator S in the acidic wash WS with water WW 10 in the manner according to the invention. After phase separation, the resulting waste WW 11, which contains all leached sulfuric and nitric acid, together with the obtained from the exhaust treatment of the nitration in an absorber A nitric acid WNA either directly or after concentration in a SAC system SAC together with the final acid AS the nitration returned to the nitration or discharged as treated wastewater.

In the washing stage 2 (i.e. After phase separation, effluent WW12 having a pH in the range of 7.5 to 13, which still contains all other acidic substances from the oxidative degradation of impurities, is supplied from the alkaline scrubbing for additional treatment before being discharged into a receiving water. The nitrate ester NA 12 from the alkaline wash WA is fed into the neutral wash WN and washed with water WW 10 according to the method of the invention, so to speak single-stage. After phase separation, WW 13 wastewater WN is fed to alkaline washing stage 2 (WA) together with base. The washed nitrate ester NA 13 is discharged directly into further processing or into an intermediate storage facility.

Further embodiments, modifications, variations of the present invention will be readily apparent to and realizable by those skilled in the art upon reading the description without departing from the scope of the present invention.

The present invention will be illustrated by the following embodiments, but without limiting the present invention thereto.

EXAMPLES Washing of ethylhexyl nitrate (EHN)

In the following embodiments, the laundry of a raw material resulting from nitriding, i. H. still unwashed and derived from the nitration by-products and unreacted starting chemicals contaminated Ethylhexylnitrats described. One of the objectives is to obtain a total acidity of less than 30 ppm, calculated as nitric acid (commercial product specification).

Although in the following exemplary embodiments the process according to the invention or the device used according to the invention with ethylhexyl nitrate (EHN) as nitrate ester to be purified is illustrated, the process or the device according to the present invention is by no means limited thereto, but is also limited to any other nitrate ester, eg , B. nitrate esters from the nitration of glycerol, trimethylolpropane, propanediol, ethylene glycol, di- and triethylene glycol, etc., and transferable to any other bases for the alkaline wash as caustic soda.

Example 1: Three-stage washing of EHN (according to the invention) Example 1.1: Single stage acid laundry

Unwashed ethylhexyl nitrate (EHN) (134.7 g / min) from a continuous nitration of ethylhexanol according to EP 1 792 891 A1 with a residual content of sulfuric acid (0.13%), nitric acid (0.84%) and ethylhexanol (about 0.4%) was together with 67 g / min demineralized water and circulated washing acid in the ratio 1: 1 by means of a Jet mixer (injector) with the washing medium as a central jet at room temperature (about 21 ° C) fed into a tubular reactor, which additionally contained three static mixing elements. The relative velocity between the central jet and the EHN to be washed was about 8: 1. The residence time in the tubular reactor was not more than 5 seconds. The pressure drop over the entire tubular reactor length was about 0.9 bar (corresponding to a mixing energy of about 90 joules / l). After phase separation, the EHN still contained about 2,700 ppm of acid (indicated as nitric acid); the wash water contained about 0.25% sulfuric acid and about 1.65% nitric acid.

Example 1.2: One-stage alkaline wash

The ethylhexyl nitrate (EHN) (133.3 g / min) obtained from the acid wash according to Example 1.1, with a residual acid content of approximately 2,700 ppm (indicated as nitric acid) together with 67 g / min of an ammonia (0.16%). , ie, 10% excess) containing aqueous solution and circulated wash liquor in the ratio 1: 1 by means of a jet mixer (injector) with the wash medium as a central jet at room temperature (about 21 ° C) fed into a tubular reactor, which in addition three static mixing elements contained. The relative velocity between the central jet and the EHN to be washed was about 8: 1. The residence time in the tubular reactor was not more than 5 seconds. The pressure drop over the entire tubular reactor length was about 0.9 bar (corresponding to a mixing energy of about 90 joules / l). After phase separation, the EHN still contained about 29 ppm acid (indicated as nitric acid).

Example 1.3: One-stage neutral wash

The ethylhexyl nitrate (EHN) (133 g / min) having a residual acid content of about 29 ppm (stated as nitric acid) originating from the alkaline wash according to example 1.2 was mixed with 67 g / demineralized water and circulating wash water in a ratio of 1 : 1 by means of a jet mixer (injector) with the washing medium as a central jet at room temperature (about 21 ° C) fed into a tubular reactor, which additionally contained three static mixing elements. The relative velocity between the central jet and the EHN to be washed was about 8: 1. The residence time in the tubular reactor was not more than 5 seconds. The pressure drop across the entire tubular reactor length was about 0.9 bar (corresponding to a mixing energy of about 90 joules / l). After phase separation, the EHN still contained about 0.1 ppm acid (indicated as nitric acid).

Example 2: Washing of EHN (comparison) Example 2.1: One-stage alkaline wash

Ethyl hexyl nitrate (EHN) (133.3 g / min) from an acidic wash as described in Example 1.1, with a residual acid content of about 2,700 ppm (indicated as nitric acid) together with 67 g / min ammonia (0, 16%, ie 10% excess) containing aqueous solution in a ratio of 1: 1 by means of a jet mixer (injector) with the washing medium as a central jet at room temperature (about 21 ° C) fed into a tubular reactor, which, however, no static Containing mixing elements. The relative velocity between the central jet and the EHN to be washed was about 8: 1. The residence time in the tubular reactor was not more than 5 seconds. The pressure drop over the entire tubular reactor length was about 0.10 bar (corresponding to a mixing energy of about 10 joules / l). After phase separation, the EHN still contained about 1200 ppm of acid (indicated as nitric acid).

Example 2.2: One-stage neutral wash

The ethylhexyl nitrate (EHN) (133.3 g / min) obtained from the alkaline wash according to Example 2.1 with a residual acid content of about 1200 ppm (indicated as nitric acid) was mixed with 67 g / min demineralized water and circulated wash water in the ratio 1: 1 by means of a jet mixer (injector) with the washing medium as a central jet at room temperature (about 21 ° C) fed into a tubular reactor which contained no static mixing elements. The relative velocity between the central jet and the EHN to be washed was about 8: 1. The residence time in the tubular reactor was not more than 5 seconds. The pressure drop over the entire tubular reactor length was about 0.10 bar (corresponding to a mixing energy of about 10 joules / l). After phase separation, the EHN still contained about 456 ppm of acid (indicated as nitric acid).

Example 3: One-stage washing of EHN (according to the invention)

Unwashed ethylhexyl nitrate (EHN) (134.7 g / min) from a continuous nitration of ethylhexanol according to EP 1 792 891 A1 with a residual content of sulfuric acid (0.13%), nitric acid (0.84%) and ethylhexanol (about 0.4%) was combined with 67 g / min of an ammonia (0.6%) containing aqueous solution and in a circle guided wash liquor in the ratio 1: 1 by means of a jet mixer (injector) with the washing medium as a central jet at room temperature (about 21 ° C) fed into a tubular reactor, which additionally contained six static mixing elements. The relative velocity between the central jet and the EHN to be washed was about 8: 1. The residence time in the tubular reactor was not more than 5 seconds. The pressure drop across the entire tube reactor length was about 1.8 bar (corresponding to a mixing energy of about 180 joules / l). After phase separation, the EHN still contained about 26 ppm acid (indicated as nitric acid).

Claims (15)

1. Method for the removal of impurities arising during the preparation of aliphatic or cycloaliphatic nitric acid esters (nitrate esters), in particular for the removal of impurities from raw nitric acid esters obtained during the nitration of nitratable mono- or polyhydric aliphatic or cycloaliphatic alcohols after separation of the raw nitric acid ester, resulting from the nitrating acid by treatment with at least one washing agent (washing medium), wherein the method comprises the following method steps:

   (a) the raw nitric acid esters are first brought into contact with a washing agent, wherein the raw nitric acid esters and the washing agent are so distributed in one another such that an emulsion results; and

   (b) subsequently, the resulting emulsion is fed into a tubular reactor, wherein the tubular reactor is provided with mixing elements, in particular for introducing additional mixing energy, such that the impurities initially present in the raw nitric acid esters are at least partially removed during the passage of the emulsion through the tubular reactor and/or such that during the passage of the emulsion through the tubular reactor, the impurities initially present in the raw nitric acid esters are at least partially transferred into the washing agent and/or neutralized thereby.
2. Method according to claim 1,
   characterized in that
   the nitric acid esters to be purified are selected from (i) nitric acid esters of aliphatic or cycloaliphatic monoalcohols, in particular linear or branched aliphatic or cycloaliphatic monoalcohols, in particular of hexanoates, heptanoans, octanols, ethylhexyl alcohol and cyclohexanol; (ii) nitric acid esters of dihydric aliphatic alcohols, in particular ethylene glycol and propylene glycol and their oligomers and polymers, such as ethylene diglycol or propylene diglycol, ethylene triglycol or propylene triglycol, and polyethylene glycol or polypropylene glycol; (iii) nitric acid esters of trivalent aliphatic alcohols, in particular of trimethylolethane and glycerol; (iv) nitric acid esters of tetrahydric or polyhydric aliphatic alcohols, in particular pentaerythritol and dipentaerythritol.
3. Method according to claim 1 or 2,
   characterized in that
   the mixing elements are static mixing elements and/or are formed as static mixing elements; and/or
   the mixing elements, in particular the static mixing elements, are fixed on the inside in the tubular reactor, in particular to the inner walls of the tubular reactor (permanently or detachably); and/or
   the mixing elements are designed as insertion elements, in particular wherein the insertion elements may be inserted into the tubular reactor and/or positioned in the tubular reactor according to the number and/or position; and/or
   the mixing elements are designed as plates, in particular baffle or deflection plates, as diaphragms, as static mixers or as flow dividers; and/or
   1 to 15 mixing elements, in particular 2 to 15 mixing elements, preferably 2 to 10 mixing elements, particularly preferably 2 to 5 mixing elements, are arranged in the tubular reactor; and/or
   a (volume-related) mixing energy of 20 to 1000 joules/liter, preferably 25 to 500 joules/liter, particularly preferably 30 to 200 joules/liter, is introduced into the tubular reactor, in particular by means of the mixing elements; and/or
   the pressure drop per mixing element is 0.2 bar to 3.0 bar, preferably 0.3 to 1.5 bar, particularly preferably 0.3 to 0.8 bar.
4. Method according to one of the preceding claims,
   characterized in that
   the emulsion is prepared in step (a) by means of a dispersing device, in particular by means of a mixing element;
   in particular wherein a jet mixer or a pump, in particular a jet pump, is used as a dispersing device, in particular as a mixing member; and/or
   in particular wherein the dispersing device, in particular the mixing element, produces a propulsion jet (central jet) and an annular jet surrounding the propulsion jet, in particular wherein the propulsion jet is formed by the washing agent and the annular jet by the raw nitric acid esters to be purified, and/or
   in particular wherein a jet mixer or a jet pump (injector) is used as the dispersing device, in particular as the mixing element, in particular wherein the jet mixer or the jet pump produces a preferably central propulsion jet and an agent surrounding the propulsion jet, in particular in the form of an annular jet, in particular wherein the propulsion jet is formed by the washing agent and the annular jet by the raw nitric acid esters to be purified; and/or
   in particular wherein the dispersing device, in particular the mixing element, produces propulsion jet (central jet) and an annular jet surrounding the propulsion jet, wherein the propulsion jet is formed by the washing agent and the annular jet by the raw nitric acid esters to be purified and/or in particular wherein the ratio of the velocities between the propulsion jet, on the one hand, and the annular jet surrounding the propulsion jet, on the other hand, is adjusted in the range from 1: 6 to 35 : 1, preferably in the range from 1 : 2 to 25 : 1, particularly preferably in the range from 1 : 1 to 12 : 1, and/or
   in particular wherein the dispersing device, in particular the mixing element, is connected upstream of the tubular reactor, in particular directly upstream, in particular wherein the dispersing device, in particular the mixing element, passes into the tube reactor; and/or
   in particular wherein the dispersing device, in particular the mixing element, is integrated into the tubular reactor and/or is a component of the tubular reactor.
5. Method according to one of the preceding claims,
   characterized in that
   the residence time of the raw nitric acid esters to be purified in the tubular reactor is 0.05 to 130 seconds, preferably 0.1 to 70 seconds, more preferably 1 to 35 seconds; and/or
   the mass ratio between the nitric acid esters to be purified, on the one hand, and the washing agent, in particular freshly added washing agent, on the other hand, lies in the range from 250 : 1 to 1 : 20, preferably in the range from 120 : 1 to 1 : 8, more preferably in the range from 12 : 1 to 1 : 3; and/or
   the mass ratio between the nitric acid esters to be purified and the washing agent in the tubular reactor and/or washing apparatus is adjusted in the range from 30 : 1 to 1 : 6, preferably in the range from 15 : 1 to 1 : 5, particularly preferably in the range from 6 : 1 to 1 : 3; and/or
   the washing agent is liquid under method conditions, in particular at temperatures above 5 °C, preferably at temperatures above 25 °C and at atmospheric pressure, and is preferably water-based, preferably water; and/or
   the method is carried out continuously; and/or
   the method is used for carrying out an acidic wash and/or a basic wash and/or a neutral wash of the raw acid esters to be purified.
6. Method according to one of the preceding claims,
   characterized in that
   a base is added to the washing agent, in particular for performing a basic wash, in particular wherein the base is selected from the group consisting of inorganic hydroxides, carbonates, hydrogencarbonates and ammonia, as well as mixtures or combinations thereof, preferably from the group consisting of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, ammonia, ammonium carbonate as well as mixtures or combinations thereof, and/or in particular wherein the content of base in the washing agent is from 0.01 to 0.4 mol/l, preferably from 0.02 to 0.2 mol/l, and/or in particular wherein the content of base in the washing agent is at least double the amount of alkali metal salts required for the neutralization of all substances formed as impurities and forming base salts.
7. Method according to one of the preceding claims,
   characterized in that
   the method, in particular method steps (a) and (b), is/are repeated and/or carried out several times, wherein the (partially) purified nitric acid esters resulting from a respective method cycle are fed back into the subsequent method cycle;
   in particular wherein at least one method cycle is carried out as basic washing and/or with a basic washing agent, and at least one subsequent method cycle is carried out as neutral washing and/or with a neutral washing agent; and/or
   in particular two, preferably three subsequent method cycles are carried out, which optionally comprise ("acidic wash") followed by a second wash with a basic washing agent ("basic wash") followed again by a third wash with a neutral washing agent ("neutral wash").
8. Method according to one of the preceding claims,
   characterized in that
   the raw nitric acid esters to be purified are subject to conditions and/or the raw nitric acid esters to be purified are optionally dissolved in an inert solvent; and/or
   in method step (b), separation of the nitric acid esters freed from the impurities from the washing agent, preferably in a phase separation device (separator); and/or
   the washing agent is recycled, in particular after separation of the nitric acid esters, which are freed from the impurities from the washing agent.
9. Use of a device (plant) for the removal of impurities arising during the preparation of aliphatic or cycloaliphatic nitric acid esters (nitrate esters), in particular for the removal of impurities from aliphatic or cycloaliphatic alcohols obtainable during nitration of monovalent or polyvalent aliphatic or cycloaliphatic alcohols after removal of the raw nitric acid esters resulting from the nitrating acid, by treatment with at least one washing agent, in particular for carrying out a method according to one of the preceding claims,
   wherein the apparatus comprises the following means:

   (a) at least one dispersing device, in particular at least one mixing element, for contacting and emulsifying raw nitric acid esters to be purified, on the one hand, and washing agent on the other hand;

   (b) downstream of the dispersing device is arranged a tubular reactor for supplying the emulsion of nitric acid esters to be purified in the dispersing device, on the one hand, and washing agent on the other hand, wherein the tubular reactor is provided with mixing elements for the introduction of additional mixing energy, so that, during the passage of the emulsion through the tubular reactor, the impurities initially present in the nitric acid esters are at least partially removed and/or so that, during the passage of the emulsion through the tubular reactor, the impurities initially present in the nitric acid esters are at least partially converted into the washing agent and/or neutralized thereby;

   (c) downstream of the tubular reactor is arranged a separation device, in particular a separation device (separator) to separate the nitrated products, which are freed from the impurities from the washing agent.
10. Use according to claim 9,
    characterized in that
    the mixing elements are static mixing elements and/or are designed as static mixing elements; and/or
    the mixing elements, in particular the static mixing elements, are fixed on the inside in the tube reactor, in particular connected to the internal walls of the tubular reactor; and/or
    the mixing elements are designed as insertion elements, in particular wherein the insertion elements may be inserted into the tubular reactor and/or positioned in the tubular reactor according to the number and/or position; and/or
    the mixing elements are designed as plates, in particular baffle or deflection plates, as diaphragms, as static mixers or as flow dividers; and/or
    1 to 15 mixing elements, in particular 2 to 15 mixing elements, preferably 2 to 10 mixing elements, particularly preferably 2 to 5 mixing elements, are arranged in the tubular reactor; and/or
    in particular, through the mixing elements, a (volume-related) mixing energy of 20 to 1000 joules/liter, preferably 25 to 500 joules/liter, particularly preferably 30 to 200 joules/liter, is introduced into the tubular reactor; and/or
    the pressure drop per mixing element is 0.2 bar to 3.0 bar, preferably 0.3 to 1.5 bar, particularly preferably 0.3 to 0.8 bar.
11. Method according to claim 9 or 10,
    characterized in that
    the dispersing device, in particular the mixing element, is designed as a jet mixer or a pump, in particular a jet pump (injector); and/or
    the dispersing device, in particular the mixing element, is designed in such a way that it produces a propulsion jet (central jet) and an annular jet surrounding the propulsion jet; and/or
    the dispersing device, in particular the mixing element, is designed as a jet mixer or jet pump (injector), in particular wherein the jet mixer or the jet pump is so designed that a preferably central propulsion jet and a medium surrounds the propulsion jet, in particular in the form of an annular jet.
12. Method according to one of the claims 9 to 11,
    characterized in that
    the dispersing device, in particular the mixing element, is connected upstream of the reactor, in particular directly upstream, in particular wherein the dispersing device, in particular the mixing element, passes into the tubular reactor; or else
    the dispersing device, in particular the mixing element, is integrated into the tubular reactor and/or is a component of the tubular reactor.
13. Use of a production plant for the production of nitric acid esters of monohydric or polyhydric aliphatic or cycloaliphatic alcohols and/or for the nitration of monohydric or polyhydric aliphatic or cycloaliphatic alcohols with subsequent purification of the nitrided raw products formed during the nitration,
    wherein the production plant comprises the following units:

    (a) a nitration unit for the preparation of nitric acid esters of monohydric or polyhydric aliphatic or cycloaliphatic alcohols and/or for the nitration of monohydric or polyhydric aliphatic or cycloaliphatic alcohols, in particular with one or more corresponding reaction vessels for carrying out the nitriding reaction(s);

    (b) optionally, in the production line downstream from the nitrating unit, a dividing device, in particular a separation device (separator), in particular for separation of the nitrating acid from the nitrided raw products (raw nitric acid esters);

    (c) in the production line downstream of the nitriding unit and the optionally provided separation device, a washing device for carrying out washing of the nitrided raw products, wherein the washing device comprises:

    - at least one dispersing device, in particular at least one mixing element, for contacting and emulsifying raw nitric acid esters to be purified, on the one hand, and washing agent, on the other hand; and,

    - downstream of the dispersing device is arranged a tubular reactor for the introduction of emulsion produced from the raw nitric acid esters in the dispersing device, on the one hand, and the washing agent, on the other hand, wherein the tubular reactor is provided with mixing elements for the introduction of additional mixing energy, so that, during the passage of the emulsion through the tubular reactor, the impurities initially present in the raw nitric acid esters are at least partially removed, and/or so that during the passage of the emulsion through the tubular reactor, the impurities initially present in the raw nitric acid esters are at least partly transferred into the washing agent and/or neutralized thereby;

    (d) if appropriate, a stirrer tank is arranged downstream of the washing device in the production line, in particular for increasing the contact and/or residence time between nitric acid esters, on the one hand, and the washing agent, on the other hand;

    (e) a stirrer tank is optionally arranged downstream of the washing device in the production line and, in particular a separation device (separator), in particular for separating the nitric acid esters, which are freed from the impurities from the washing agent.
14. Use according to claim 13,
    characterized in that
    the mixing elements are static mixing elements and/or are designed as static mixing elements; and/or
    the mixing elements, in particular the static mixing elements, are fixed on the inside in the tubular reactor, in particular to the inner walls of the tubular reactor; and/or
    the mixing elements are designed as insertion elements, in particular wherein the insertion elements may be inserted into the tubular reactor and/or positioned in the tubular reactor according to the number and/or position; and/or
    the mixing elements are designed as plates, in particular baffle or deflection plates, as diaphragms, as static mixers or as flow dividers; and/or
    1 to 15 mixing elements, in particular 2 to 15 mixing elements, preferably 2 to 10 mixing elements, particularly preferably 2 to 5 mixing elements, are arranged in the tubular reactor; and/or
    a volume-related mixing energy of 20 to 1000 joules/liter, preferably 25 to 500 joules/liter, particularly preferably 30 to 200 joules/liter, is introduced into the tubular reactor, in particular through the mixing elements; and/or
    the pressure drop per mixing element is 0.2 bar to 3.0 bar, preferably 0.3 to 1.5 bar, particularly preferably 0.3 to 0.8 bar.
15. Use according to claim 13 or 14,
    characterized in that
    the dispersing device, in particular the mixing element, is designed as a jet mixer or a pump, in particular a jet pump (injector); and/or
    the dispersing device, in particular the mixing element, is designed so that it produces a propulsion jet (central jet) and an annular jet surrounding the propulsion jet; and/or
    the dispersing device, in particular the mixing element, is designed as a jet mixer or jet pump, in particular wherein the jet mixer or the jet pump (injector) are so designed that a preferably central propulsion jet and a medium surrounding the propulsion jet, in particular in the form of an annular jet, may be generated; and/or
    the dispersing device, in particular the mixing element, is connected upstream of the reactor, in particular directly upstream, in particular wherein the dispersing device, in particular the mixing element, passes into the tubular reactor; and/or
    the dispersing device, in particular the mixing element, is integrated into the tubular reactor and/or is a component of the tubular reactor.

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